Hello,
From the description of your symptoms, it can be hives. In most of the cases of chronic urticaria, the underlying pathology is idiopathic i.e it is not linked to any cause. Causes of urticaria include Drugs and Chemicals, contactants, certain foods, infections and systemic diseases.
Treatment is by oral antihistamines like Benadryl or Claritin and calamine lotion. Topical steroids are also helpful. If the symptoms do not improve then oral steroids may be needed and systemic diseases should be ruled out.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Probably a systemic allergy of some sort. My guess would be allergy to either the Prednisone or what ever other medication you were taking prior to the Prednisone. I'm having a similar issue with a different medication and will likely have to do the same thing.